Current and fluid conducting arrangements

ABSTRACT

Apparatus is provided for the rectification of a power source for the use ultimately in such applications as electroplating, with the apparatus utilizing electrical conducting materials in the form of tubing for conveying simultaneously cooling fluids directly to areas adjacent parts requiring cooling during operation, and electrical current over substantial portions of the circuitry of the apparatus. In addition, new heat sink arrangements are provided for more even distribution of cooling fluids over parts to be cooled, and new clamping arrangements are provided for even distribution of pressure on parts being held and which clamping arrangements are readily manipulated by a single adjustment.

United States Patent Beasley et al.

[54] CURRENT AND FLUID CONDUCTING ARRANGEMENTS [72] Inventors: Jack O. Beasley, Holmdel; Paul J. Mohary, Toms River, both of NJ.

[73] Assignee: M 8: T Chemicals Inc., Greenwich, Conn.

[22] Filed: Apr. 16, 1971 21 App]. No.: 134,727

[52] U.S. Cl. ..321/8 C, 317/234 B [51] Int. Cl. ..l-l02m 7/00 [58] Field olSearch .......3l7,/234 B;32l/8,8C

[56] References Cited UNITED STATES PATENTS 3,173,061 3/1965 Storsand ..321/8 C 3,275,921 9/1966 Fellendorf et al. .....321/8 C 3,370,216 2/1968 Bowar et al. "317/234 B June 6, 1972 FOREIGN PATENTS OR APPLICATIONS 981,148 1/1965 GreatBritain ..321/8C 1,513,932 9/1969 Germany ..32l/8C Primary Examiner-William M. Shoop, Jr. Attorney-Kenneth G. Wheeless, Robert P. Grindle and Robert P. Auber [57] ABSTRACT Apparatus is provided for the rectification of a power source for the use ultimately in such applications as electroplating, with the apparatus utilizing electrical conducting materials in the form of tubing for conveying simultaneously cooling fluids directly to areas adjacent parts requiring cooling during operation, and electrical current over substantial portions of the circuitry of the apparatus. In addition, new heat sink arrangements are provided for more even distribution of cooling fluids over parts to be cooled, and new clamping arrangements are provided for even distribution of pressure on parts being held and which clamping arrangements are readily manipulated by a single adjustment.

8 Claims, 10 Drawing Figures PATENTEDJUH s 1972 3,668 506 sum 1 or 5 Hal INVENTORS. JACK O. BEASLEY PAUL J. MOHARY WP.

ATTORNEY PATENTEDJUH 6 I972 3. 668 506 SHEET 2 0F 5 F IG. 2

I ,0 -Llmnmuiflmflflir INVENTORS. JACK O BEASLEY y PAUL J. MOHARY mew ATTORNEY PATENTEDJUH 6 m2 3,668,506

JACK 0- BEASLEY PAUL J. MOHARY magm ATTORNEY PATENTEDJun 6 I972 SHEET 01'' 5 INVENTORS.

JACK O. BEASLEY PAUL J. MOHARY NEW ATTORNEY PATENTEDJUN s I972 SHEET 5 0F 5 INVENTORS. JACK O. BEASLEY BY PAUL J. MOHARY W m m UUUUU'" ATTORNEY Generally, this invention relates to devices for the rectification of a power source for particular applications, such as, for example, electroplating, electric motors and other electrical devices requiring a particular kind of electrical power source.

More particularly, this invention relates to a circuitry arrangement for rectifiers in which the operating temperatures of various components of the rectifier must be controlled by the application of some kind of cooling, and to a circuitry arrangement for rectifiers providing the dual function of carrying current and cooling fluid, all in a manner which makes the rectifiers, in accordance herewith, appropriate and advantageous from a commercial standpoint. It is to make possible the use of high current-low voltage silicon controlled rectifiers (SCRs) as both rectifiers and controllers in the secondary circuit of a power supply to which this invention is specifically applicable.

In the past, circuits pertaining to this type of power supply used SCRs in the high voltage side of a step-down transformer in a back-to-back arrangement in the delta connection of the transformer, or in the line circuit. These SCRs would control the AC voltage on the secondary of the transformer. Other means of rectification, such as silicon diodes, would then be connected generally in a bridge, double wye with the interphase or star connection in the high current-lower voltage secondary circuit.

If SCRs were used in the secondary circuit connected as the diodes described above, the SCRs would function in the same manner as the combination of the above-noted SCRs and secondary diodes. However, until recently, SCR devices were not available to handle large currents in the secondary without the use of paralleling devices, which were found to be too costly in this application for routinely utilized rectifiers on any appropriate commercial scale. Recently, SCRs have been devised which will accommodate. the higher current. However, these devices require extensive cooling in order to make them function in an economical manner by utilizing their maximum capacity. Thus, extensive and complicated cooling apparatus is necessary in order to maintain the higher current capacity SCRs available today. With such an arrangement, however, the cost of the entire rectifier apparatus is again increased to the point making them inappropriate for routine commercial application.

According to this invention, however, methods and apparatus are provided whereby rectification of a power source is achieved utilizing the high current capacity SCRs which function in the same manner as the prior art combination of primary SCRs. and secondary diodes in the absence of the necessity of any paralleling devices, and in a manner making I the apparatus economically attractive. The above is achieved by utilizing a simplified arrangement of circuitry for the rectifier in which the tubing used for carrying cooling fluids to those parts of the rectifier needing cooling are made of electrical conducting materials so that the tubing can be used simultaneously to carry the cooling fluid and current. In addition,

the arrangements, in accordance herewith, provide for the carrying of the cooling fluid to areas immediately adjacent the parts requiring cooling and in a manner whereby the cooling fluid is dispersed in an even fashion over the area immediately adjacent the part to be cooled.

The arrangements here provide for appropriately configured heat sinks disposed on each side of the SCRs in a sandwich fashion so as to obtain the maximum amount of cooling from cooling fluid flowing therethrough. In addition, the invention, in accordance herewith, provides a particular sandwich arrangement of heat sinks adjacent the SCRs with a clamping arrangement providing even pressure on either side of the SCR so as not to interfere with the functioning thereof, as well known, and with the clamping arrangement requiring a single adjustment in order to achieve this even pressure.

One object of the invention, therefore, is to provide a simple electrical system for rectification of apower source in which SCRs are utilized in the high current-lower voltage secondary circuit.

Another object of the invention is to provide for the simultaneous carrying of cooling fluids to those areas immediately adjacent parts needed to be cooled in the rectifiers simultaneously with carrying the current requirements and/or connections for the rectifier.

A further object of this invention is utilization of SCRs in the high current-lower voltage secondary circuit of rectifiers in the absence of the need for the use of paralleling devices. Still another object of this invention is to provide a heat sink arrangement disposed immediately adjacent the parts to be cooled so as to carry the cooling fluid to that place most appropriate for providing the cooling desired and in a manner providing even dispersion of the cooling fluid over the entire area desired to be cooled. In addition, it is a further object of this invention to provide a sandwich arrangement of heat sinks disposed on two sides of the SCRs with the entire sandwich arrangement being held in a clamping device which provides even pressure on each side of the SCRs as required and as is well known in the art, with this even pressure being achieved by a single adjustment in the clamping arrangement.

Other objects and advantages of this invention will be apparent from the following description, the accompanying drawings, and the appended claims.

FIG. 1 is a front elevational view of a rectifier with the panels removed for clarity and including circuit and mechanical aspects of apparatus embodying and for practicing this invention;

. FIG. 2 is a side elevational view of the apparatus of FIG. 1 as viewed from the right hand side thereof;

FIG. 3 is a top plan view of the apparatus of FIG. 1;

FIG. 4 is a sectional view along lines AA in FIG. 1 and showing the sandwich arrangement of heat sinks and SCR and further mechanical aspects of apparatus embodying and for practicing this invention;

FIG. 5 is a diagrammatic or flow sheet indication of the dual fluid and electrical circuitry arrangement embodying and for practicing this invention;

FIG. 6 is a diagrammatic or schematic indication of the electrical circuit for a rectifier and including circuit and mechanical aspects of apparatus embodying and for practicing this invention; FIG. 7 is a top plan view of one heat sink arrangement, and with the top removed so as to show the internal arrangement thereof and mechanical aspects of apparatus embodying and for practicing this invention;

FIG. 8 is a sectional view along lines BB of FIG. 7;

FIG. 9 is a top plan view of another heat sink arrangement embodying and for practicing this invention with the top removed for clarity; and v FIG. 10 is a sectional view along lines CC of FIG. 9.

Referring to the drawings in which like characters of reference refer to like parts throughout the several views thereof, FIG. 1 illustrates the invention as employed in a conventional rectifier for rectification of a power source for application to, for example, electroplating.

In FIG. 1 a rectifier is designated generally as 10, with the outer paneling removed for clarity, and with the rectifier being rigidly disposed on a support 12. A three-phase transformer 13 is shown (FIG. 2). The negative output terminal 11 is shown in the upper lefi hand comer of FIG. 1 with both the current and the cooling fluid brought into the rectifier by this negative output terminal in the form of tubing made of an appropriate electrical conductive material such as, for example, copper or aluminum. For purposes of clarity, dielectric tubing is shown with shading in the form of dots, while tubing of electrical conducting material is shown without shading. Tubing 11 connects to the center taps 59, 60 and 61 of the threephase transformer 13 behind plates 14, 15 and 16, respectively, in FIG. 1. The cooling fluid continues on from the center tap positions through electrical conducting tubing 17 to T in tersection 28. Thereafter, the cooling fluid flows through dielectric tubing which may be of any appropriate non-conducting material such as, for example, nylon. Dielectric tubing 18 conducts the cooling fluid to the bottom of FIG. 1 to supply the fluid to heat sinks 19, 20 and 21 disposed immediately below SCRs 24, 25 and 26, respectively.

The cooling fluid proceeds through the three heat sinks 19, 20 and 21, and thereafter passes from each heat sink into electrical conducting tubing 27 which forms part of the three secondary windings of the transformer (FIGS. 2 and The fluid flow then comes out of the three secondaries as through lines 22 which are electrical conducting tubing to supply heat sinks 37, 38 and 39 disposed immediately adjacent the bottom of SCRs 42, 41 and 40, respectively, at the top of FIG. 1. The fluid flowing through these three small heat sinks is then collected in dielectric tubing 36 to be led to outlet tubing 44 -which is comprised of electrical conducting material and which serves as the positive output terminal for the rectifier arrangement.

At T intersection 28 in FIG. 1, cooling fluid is carried through dielectric tubing 29 to an additional T intersection where the line divides into dielectric tubing 30 carrying cooling fluid to large heat sink 31 which extends longitudinally over allthree SCRs 24, 25 and 26 disposed at the bottom of FIG. 1. Also leading from line 29 is dielectric tubing 34 which carries cooling fluid to large heat sink 35 extending longitudinally over SCRs 40, 41 and 42 at the top of FIG. 1. The fluid flowing through these large heat sinks 31 and 35 is collected into the electrical conducting outlet tubing 44.

- FIG. 2 is a side view in elevation'of the showing in FIG. 1 from the right hand side thereof and indicates the supporting structure in th e form of angle brackets 46 for supporting each end of the combined SCR and heat sink assemblies at the bottom and the top of the rectifier device. I

FIG. 3 is a top plan view of the arrangement in FIG. 1 and shows the supply line 11 feeding to each of the center taps 59, 60 and 61 of the secondary, as well as a view of longitudinally extending large heat sink 35 disposed over all three of the top SCRs 40, 41 and 42.

FIG. 4 is a view in section taken along lines A-A in FIG. 1 and shows the sandwich-type supporting arrangement for the SCRs disposed between the large heat sink 35 extending above SCR 41, as well as the other SCRs 40 and 42, not shown, and individual heat sink 38 disposed immediately below SCR 41.

As can be seen in FIG. 4, bearing plates 56 and 57 are disposed immediately below and above SCR 41. Tie rods 52 and 53 are shown disposed on each side of the sandwich arrangement in diametrically opposed positions, and with the tie rods 52 and 53 extending through bearing plates 56 and 57 to and through spring plates 50 and 51 and adjusting screw bearing plate 64. The bores in the various bearing and spring plates are larger than the tie rods 52 and 53 passing through the bores so asto allow movement between the tie rods and the various plates. The tie rods are insulated from the various plates and are held firmly in place against spring plate 50 as by insulators 62 and 63. Adjusting screw 58 is disposed in the center of top spring plate 50, passes therethrough and bears against adjusting screw bearing plate 64. The configuration of the bottom of adjusting screw 58 is semi-circular so as to bear evenly against the adjusting screw bearing plate 64 so as not to mar the upper surface of heat sink 35.

Thus, by screwing down adjusting screw 58 through supporting plate 50 against the surface of the bearing plate 64, an interaction between the various bearing and spring plates and the tie rods 52 and 53 is achieved so as to maintain an equal supporting pressure on the top and the bottom of the SCRs so as to help maintain the SCRs in proper operating form since, as well known, an SCRs operating capacity and/or ability is effected if it is not mounted in a manner so that an even supporting pressure is provided on diametrically opposite sides thereof.

Referring to FIG. 5, a diagrammatic or flow sheet indication of the pipe and electrical connections of the device, in accordance herewith, is shown. Those lines shown as double lines are the electrical conducting tubing, while those lines shown in single line form are dielectric tubing. The supply is shown as line 11 of electrical tubing leading to center taps 59, 60 and 61 of the secondary of transformer 13. From there, the tubing leads to T intersection 28 which feeds dielectric tubing 18, which in turn feeds the three small heat sinks 19, 20 and 21 disposed immediately below the SCRs as shown in FIG. 1. From these three small heat sinks, the cooling fluid is collected and flows through electrical conducting tubing 27 which forms part of the secondary winding of the transformer and from there flows through electrical tubing 22 to feed cooling fluid to the three small heat sinks 39, 40 and 41 disposed at the bottom of the SCRs at the top of FIG. 1. From these three small heat sinks, the cooling fluid is collected as through dielectric tubing 36 into outlet line 44 which is electrically conducting material.

At T intersection 28, fluid flows through dielectric tubing 29 and 30 to the large heat sink 31 disposed immediately above the three SCRs shown at the bottom of FIG. 1 From large heat sink 31, the fluid flows to electrical conducting outlet line 44. Also from T intersection 28, as through lines 29 Y and 34, cooling fluid is fed to large heat sink 35 and from there flows into electrical conducting outlet tubing 44.

For the purposes of completing the connections in the diagram shown in FIG. 5, it should be noted that those parts designated 67 are brass female connectors, those parts designated 68 are brass union elbows and those parts designated 69 are-brass union tees.

Although the above arrangement exemplifies the invention, in accordance herewith, it is to be understood that the invention is not limited to that specific arrangement. For example, a single longitudinally extending large heat'sink has been utilized having a larger capacity than large heat sinks 31 and 35 described above. With such an arrangement, three each of the SCRs are arranged along the longitudinal extent of each side of the larger capacity large heat sink with the smaller heat sinks, such as 19, 20 and 21 disposed adjacent each SCR on the side thereof opposite the larger capacity large heat sink. With such an arrangement, line 29 leads from T 28 to the inlet of the larger heat sink and the outlet is connected to line 44 in the same manner as the connections for the heat sinks 31 and 35 described above.

FIG. 6 is a schematic indicationshowing one embodiment of the invention herein of a circuit diagram in which a power supply source 70 is shown for the conversion thereof of alternating current from that source to direct current suitable for employment as a power source for operating an electroplating line, for example. -As shown in FIG. 6, alternating current power lines 71, 72 and 73 are connected to a starter, shown in a schematic form as dotted line 76 with the switch thereof connected to lines 85, 86 and 87. These lines are in turn connected to the primary windings 80, 81 and 82 of transformer 77 having a single core 78.

As is shown further, the secondary windings 79 of the transformer 77 are connected to the individual SCRs 95 of semiconductor section 115. These individual SCRs are in turn each connected to the direct current positive terminal 90. The negative output terminal 88 has a shunt 96 disposed therein, which shunt is connected as through line 99 to a shunt relay 100, all in well known fashion. In addition, the shunt is connected as through lines 97 and 98 to an SCR firing regulator which in turn is connected to an SCR firing assembly, both of which are not shown, and all in well known manner. A volt meter 91 is connected between lines 88 and as by line 92 and a resistor 93 is also connected between lines 88 and 90 as by line 94, again all in well known fashion. The terminals 101 and 102 connected to the individual SCRs are in turn connected to the SCR firing assembly, not shown, in order to control the firing sequence of the SCRs.

FIG. 7 is a top plan view of one heat sink arrangement such as the longitudinally extending heat sink 35 as shown in FIG. 1. The top of the heat sink has been removed so as to show the internal arrangement of the heatsink 35 having an inlet 104 and an outlet 105. The inlet channel 104 feeds each of the iongitudinally extending channels 106 ,in the heat sink thus dispersing cooling fluid evenly over the entire extent of the heat sink.

FIG. 8 is a section taken along lines 88 of FIG. 7. With such an arrangement, cooling fluid is made to flow evenly over the entire surface area of the heat sink thus making it a much more effective arrangement for providing a cooling environment immediately adjacent the surface areas of theheat sink. In addition, a much larger heat exchange surface is presented for effective cooling.

FIG. 9 is a top plan view of a heat sink similar in arrangement to that of FIG. 7 but showing the small individual heat sink, such as 19 in FIG. 1 and having an inlet channel 107 and an outlet channel 108 with individual longitudinally extending dispersing channels 109 extending between inlet and outlet channels 107 and 108.

FIG. 10 is a section taken along lines 10l0 of FIG. 9. As

can readily be seen, such an arrangement provides for an even distribution of the cooling fluid over the entire area of the heat sink, thus making it a much more effective arrangement for providing a cooling environment to those devices immediately adjacent the heat sink, such as the SCRs shown in FIG. 1.

With such an arrangement, therefore, utilizing 6 SCRs in the secondary an output up to 5,000 amps or more can be obtained without paralleling. However, it should be understood that, whereas the specific example shown was designed to operate for the rectification of alternating current into direct current for an electroplating line, this very same circuit could be redesigned so that the individual components thereof have different size characteristics, depending upon the particular installation, such as an electroplating line which is to be operated from such a circuit. As well known, such installations vary considerably depending upon the size of the installation involved and the particular kinds of electroplating being carried on. Furthermore, it is to be understood that the circuits, in accordance herewith, are useful for applications of all kinds involving devices utilizing a source of electrical power for the I operation of a variety of different kinds ofinstallations including electroplating lines,'as noted above, welding operations, electric furnaces, electric motors used to drive a variety of operations. The precise values of the various electrical and electronic components utilized in the various combinations and circuits embodying and for practicing this invention will be readily apparent to men skilled in this art after the teachings and disclosures hereof.

For example, although 6 SCRsare shown as being utilized in the secondary here, it is to be understood that different numbers of SCRs may be utilized for various purposes. For example, 12 SCRs may be used for a circuit requiring electronic reversing with 6 SCRs being used in each direction and with the circuitry being substantially similar to that disclosed in US. Pat. No. 3,450,892 to McNulty et al.

Also, it should be understood that although the arrangements described above are specifically for the utilization of silicon controlled rectifiers in the secondary, that such an arrangement can be used utilizing diodes as well, because, as is well known, diodes require substantial cooling for efficient operation.

As will be apparent from the foregoing, then, methods and apparatus are provided in accordance herewith for the rectification of a power source for specific applications in which the temperature of various components of the apparatus must be controlled, and in which SCRs are utilized in the secondary without the necessity of expensive paralleling arrangements.

The above is achieved by the direct application of cooling fluid to the areas immediately adjacent the parts to be cooled and with the tubing arrangements utilized for carrying the cooling fluid to the precise areas also being utilized simultaneously for carrying substantial portions of the electrical circuitry of the apparatus, and with the above being achieved in a manner making the apparatus economically feasible for routine rectification applications.

In addition, with the arrangements, in accordance herewith, even distribution of cooling fluid in the areas immediately adjacent the parts to be cooled is achieved by heat sinks having dispersion channels disposed therein which provide much more extensive heat exchange area. Furthermore, clamping arrangements are provided for the SCR's utilized here in appropriately aligned relationship to the adjacent heat sinks utilized for cooling the SCR's in operation and which clamping arrangements provide simultaneously for an even application of pressure on diametrically opposite sides of the SCRs so as to not afiect their operating ability and with the clamping arrangement being controlled by a single adjusting screw.

While the methods and fOITllS of apparatus herein describe and constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise methods or forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

We Claim:

1. Apparatus for supplying direct current from a rectifier and having a cooling fluid source, an alternating current source, and a transformer connected to said alternating current source and having a three-phase primary and a threephase secondary, the combination which comprises a plurality of silicon controlled rectifiers in said secondary, a plurality of heat exchange means with individual ones of said heat exchange means disposed adjacent individual ones of said silicon controlled rectifiers, first means providing flow commu nication between said cooling fluid source and said heat exchange means, said first flow communication means also being the negative output terminal for said transformer, a positive output terminal for said transformer connected to said plurality of silicon controlled rectifiers, said positive output terminal being second flow communication means providing flow communication for said cooling fluid away from said heat exchange means, and said first and second flow communication means being dielectric in that portion thereof immediately adjacent said heat exchange means.

2. Apparatus as recited in claim 1 in which said first and second flow communication means are metallic tubing selected from the group consisting of copper and aluminum except in the dielectric portions thereof, and said dielectric portions are nylon tubing.

3. Apparatus as recited in claim 1 in which the non-dielectric portions of said first and second flow communication means are in flow communication with the secondary winding of said transformer.

4. Apparatus as recited in claim 1 in which said plurality of heat exchange means includes individual heat sinks disposed adjacent one side of each of said plurality of silicon controlled rectifiers.

5. Apparatus as recited in claim 4 in which there are six silicon controlled rectifiers arranged in longitudinally extending group of three each, which also includes a longitudinally extending heat sink adjacent each group of three silicon controlled rectifiers on the side thereof opposite said individual heat sinks, and which also includes dielectric flow communication means connected to each of said longitudinally extending heat sinks and said first and second flow communication means for providing cooling fluid flow through said longitudinally extending heat sinks.

6. Apparatus as recited in claim 5 in which said heat sinks have an inlet channel extending into a substantial portion of one end thereof, an outlet channel extending into a substantial portion of the end of said heat sink opposite said inlet channel, and a plurality of spaced apart dispersion channels extending from said inlet channel to said outlet channel and perpendicular thereto, the cross-section of said dispersion channels being substantially smaller than said inlet and outlet channels.

7. Apparatus as recited in claim 6 which includes clamping means disposed adjacent each one of said silicon controlled rectifiers for holding with equal pressure that portion of the adjacent longitudinally extending heat sink, and said adjacent individual heat sink on diametrically opposed sides of said silicon controlled rectifier to form a sandwich arrangement.

8. Apparatus as recited in claim 7 in which said clamping means is comprised of bearing plates disposed between said silicon controlled rectifier and the adjacent heat sinks, spring plates disposed against each of said heat sinks on the side thereof opposite said bearing plates, a screw bearing plate disposed against one of said spring plates, said bearing plates, said spring plates and said screw bearing plate extending beyond at least two opposed edges of said sandwich arrange- 

1. Apparatus for supplying direct current from a rectifier and having a cooling fluid source, an alternating current source, and a transformer connected to said alternating current source and having a three-phase primary and a three-phase Secondary, the combination which comprises a plurality of silicon controlled rectifiers in said secondary, a plurality of heat exchange means with individual ones of said heat exchange means disposed adjacent individual ones of said silicon controlled rectifiers, first means providing flow communication between said cooling fluid source and said heat exchange means, said first flow communication means also being the negative output terminal for said transformer, a positive output terminal for said transformer connected to said plurality of silicon controlled rectifiers, said positive output terminal being second flow communication means providing flow communication for said cooling fluid away from said heat exchange means, and said first and second flow communication means being dielectric in that portion thereof immediately adjacent said heat exchange means.
 2. Apparatus as recited in claim 1 in which said first and second flow communication means are metallic tubing selected from the group consisting of copper and aluminum except in the dielectric portions thereof, and said dielectric portions are nylon tubing.
 3. Apparatus as recited in claim 1 in which the non-dielectric portions of said first and second flow communication means are in flow communication with the secondary winding of said transformer.
 4. Apparatus as recited in claim 1 in which said plurality of heat exchange means includes individual heat sinks disposed adjacent one side of each of said plurality of silicon controlled rectifiers.
 5. Apparatus as recited in claim 4 in which there are six silicon controlled rectifiers arranged in longitudinally extending group of three each, which also includes a longitudinally extending heat sink adjacent each group of three silicon controlled rectifiers on the side thereof opposite said individual heat sinks, and which also includes dielectric flow communication means connected to each of said longitudinally extending heat sinks and said first and second flow communication means for providing cooling fluid flow through said longitudinally extending heat sinks.
 6. Apparatus as recited in claim 5 in which said heat sinks have an inlet channel extending into a substantial portion of one end thereof, an outlet channel extending into a substantial portion of the end of said heat sink opposite said inlet channel, and a plurality of spaced apart dispersion channels extending from said inlet channel to said outlet channel and perpendicular thereto, the cross-section of said dispersion channels being substantially smaller than said inlet and outlet channels.
 7. Apparatus as recited in claim 6 which includes clamping means disposed adjacent each one of said silicon controlled rectifiers for holding with equal pressure that portion of the adjacent longitudinally extending heat sink, and said adjacent individual heat sink on diametrically opposed sides of said silicon controlled rectifier to form a sandwich arrangement.
 8. Apparatus as recited in claim 7 in which said clamping means is comprised of bearing plates disposed between said silicon controlled rectifier and the adjacent heat sinks, spring plates disposed against each of said heat sinks on the side thereof opposite said bearing plates, a screw bearing plate disposed against one of said spring plates, said bearing plates, said spring plates and said screw bearing plate extending beyond at least two opposed edges of said sandwich arrangement and having bores disposed therein, tie rods extending through said bores for holding said plates and said sandwich arrangement together, and an adjusting screw extending through one of said spring plates and bearing against said screw bearing plate for urging said plates of said sandwich arrangement together on each side of said silicon controlled rectifier with equal pressure. 